Electromagnetic interference (EMI) shielding device and method for use in an optical communications system

ABSTRACT

An electromagnetic interference (EMI) shielding device and method are provided for use with an optical communications module (OCM) that is configured to be plugged into a front panel of a box or housing of an optical communications system. The EMI shielding device is mechanically coupled to an end of a housing of the OCM such that when the OCM is fully inserted through an opening formed in the front panel, the EMI shielding device comes into abutment with the front panel to form an EMI seal around the opening that prevents, or at least helps prevent, EMI from escaping from the system housing through the opening formed in the front panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in part of application Ser. No.13/543,930, filed on Jul. 9, 2012, entitled “A Z-PLUGGABLE OPTICALCOMMUNICATIONS MODULE, AN OPTICAL COMMUNICATIONS SYSTEM, AND A METHOD,”which is incorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The invention relates to optical communications systems. Moreparticularly, the invention relates to an electromagnetic interference(EMI) shielding device for use in an optical communications system.

BACKGROUND OF THE INVENTION

A parallel optical communications module is a module having multipletransmit (TX) channels, multiple receive (RX) channels, or both. Aparallel optical transceiver module is an optical communications modulethat has multiple TX channels and multiple RX channels in TX and RXportions, respectively, of the transceiver module. The TX portioncomprises components for transmitting data in the form of modulatedoptical signals over multiple optical waveguides, which are typicallyoptical fibers. The TX portion includes a laser driver circuit and aplurality of laser diodes. The laser driver circuit outputs electricalsignals to the laser diodes to modulate them. When the laser diodes aremodulated, they output optical signals that have power levelscorresponding to logic 1s and logic 0s. An optics system of thetransceiver module focuses the optical signals produced by the laserdiodes into the ends of respective transmit optical fibers held within aconnector that mates with the transceiver module.

Typically, the TX portion also includes a plurality of monitorphotodiodes that monitor the output power levels of the respective laserdiodes and produce respective electrical feedback signals that are fedback to the transceiver controller. The transceiver controller processesthe feedback signal to obtain respective average output power levels forthe respective laser diodes. The transceiver controller outputs controlsignals to the laser driver circuit that cause it to adjust themodulation and/or bias current signals output to the respective laserdiodes such that the average output power levels of the laser diodes aremaintained at relatively constant levels.

The RX portion includes a plurality of receive photodiodes that receiveincoming optical signals output from the ends of respective receiveoptical fibers held in the connector. The optics system of thetransceiver module focuses the light that is output from the ends of thereceive optical fibers onto the respective receive photodiodes. Thereceive photodiodes convert the incoming optical signals into electricalanalog signals. An electrical detection circuit, such as atransimpedance amplifier (TIA), receives the electrical signals producedby the receive photodiodes and outputs corresponding amplifiedelectrical signals, which are processed in the RX portion to recover thedata.

There is an ever-increasing demand in the optical communicationsindustry for parallel optical communications systems that are capable ofsimultaneously transmitting and receiving ever-increasing amounts ofdata. To accomplish this, it is known to combine multiple paralleloptical transceiver modules of the type described above to produce aparallel optical communications system that has a higher bandwidth thanthe individual parallel optical transceiver modules. A variety ofparallel optical transceiver modules are used in such systems for thispurpose.

FIG. 1 illustrates a perspective view of an electrical connector 2,known in the industry as a Meg-Array connector, mounted on a printedcircuit board (PCB) 3. The Meg-array connector 2 comprises a socket 4having an array of electrically-conductive ball contacts (not shown) onits bottom surface and an array of electrically conductive bladed pairs5 on its upper surface. FIG. 2 illustrates a perspective view of theMeg-array connector 2 shown in FIG. 1 after a parallel opticaltransceiver module 6, known in the industry as a Snap-12 paralleloptical transceiver module, has been plugged into the socket 4. Thesnap-12 module 6 has an array of electrical contacts (not shown) on itslower surface that come into contact with respectiveelectrically-conductive bladed pairs 5 of the Meg-Array connector 2 whenthe module 6 is pressed down in the Y-direction of an X, Y, Z Cartesiancoordinate system into the socket 4.

A receptacle 7 is disposed within an opening formed in a front panel 8of a box (not shown) for receiving an optical connector module (notshown). The optical connector module (not shown) is mated with thereceptacle 7 by inserting the optical connector module in theZ-direction through the opening formed in the front panel 8 into thereceptacle 7 such that mating features (not shown) on the inside of thereceptacle 7 engage respective mating features (not shown) on theoptical connector module (not shown). This type of mounting arrangementis known in the industry as an edge-mounted arrangement due to the factthat the front panel 8 constitutes an edge of the box in which theparallel optical transceiver modules are mounted. The optical connectormodule is mechanically and optically coupled to an end of an opticalfiber ribbon cable (not shown) having a plurality (e.g., 4, 8, 12, 24,or 48) of optical fibers.

By mounting multiple of the optical transceiver modules 6 side-by-sideon the motherboard PCB 3, an optical communications system with veryhigh bandwidth can be achieved. There are, however, disadvantagesassociated with edge-mounted arrangements of the type shown in FIG. 2.One such disadvantage is that the receptacles 7 and the respectiveoptical connector modules (not shown) are relatively wide in theX-dimension and therefore consume large amounts of space on the frontpanel 8. Because space on the front panel 8 is limited, the ability toincrease bandwidth by increasing the size of the array is also limited.

Another disadvantage associated with the edge-mounted arrangement shownin FIG. 2 is that the parallel optical transceiver modules 6 are notZ-pluggable, i.e., they cannot be plugged into and unplugged from thefront panel 8. Rather, before the top of the box has been secured inposition, the modules 6 are plugged into their respective Meg-Arraysockets 4 by placing the modules 6 over the respective sockets 4 andapplying a force in the downward Y-direction. The top of the box is thensecured in position. This makes the tasks of installing the modules 6and swapping the modules 6 out relatively difficult and time-consuming.

SUMMARY OF THE INVENTION

The invention is directed to an EMI shielding device and method. Inaccordance with an embodiment, the EMI shielding device and method areused in a Z-pluggable optical communications module (OCM). TheZ-pluggable OCM comprises a module housing, a first circuit boarddisposed within the module housing, at least one parallel opticalcommunications module (POCM) mounted on the first circuit board, and anEMI shielding device mechanically coupled to a first end of the modulehousing. The module housing is a generally rectangular module housingconfigured to be inserted through an opening formed in a front panel ofa box in a Z-direction of an X, Y, Z Cartesian Coordinate system. Whenthe module housing is fully inserted through the opening formed in thefront panel of the box in the Z-direction of the X, Y, Z CartesianCoordinate system, the EMI shielding device abuts the front panel andsurrounds the opening to form an EMI seal about the opening thatprevents, or at least helps prevent, EMI from escaping from the modulehousing through the opening.

The method comprises:

providing a Z-pluggable OCM comprising a generally rectangular modulehousing having an EMI shielding device mechanically coupled to a firstend thereof; and

fully inserting the module housing through an opening formed in a frontpanel of a box in the Z-direction of the X, Y, Z Cartesian Coordinatesystem until the EMI shielding device abuts the front panel. When theEMI shielding device is in abutment with the front panel, the EMIshielding device surrounds the opening to form an EMI seal about theopening that prevents, or at least helps prevent, EMI from escaping fromthe module housing through the opening.

These and other features and advantages of the invention will becomeapparent from the following description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a Meg-Array connector mountedon a PCB.

FIG. 2 illustrates a perspective view of the Meg-Array connector shownin FIG. 1 after a Snap-12 parallel optical transceiver module has beenplugged into the socket of the Meg-Array connector.

FIG. 3 illustrates a front perspective view of an optical communicationssystem in accordance with an illustrative embodiment.

FIG. 4 illustrates a perspective view of one of the Z-pluggable OCMsshown in FIG. 3 with one side of the housing removed to reveal theparallel OCMs and a PCB on which the parallel OCMs are mounted.

FIG. 5 illustrates a front perspective view of the opticalcommunications system shown in FIG. 3 with a portion of the box andfront panel removed to reveal an actuator mechanism for imparting motionto the Z-pluggable OCM in the downward and upward Y-directions.

FIGS. 6A-6E illustrate perspective views of an optical communicationssystem that employs a spring-loaded actuator mechanism to impart motionin the upward and downward Y-directions to a Z-pluggable OCM.

FIGS. 7A and 7B illustrate top perspective views of two of the adjacentZ-pluggable OCMs shown in FIGS. 3-5 without the box shown in FIG. 3.

FIG. 8 illustrates a top perspective view of a plurality of adjacentZ-pluggable OCMs shown in FIGS. 3-5 plugged into adjacent openingsformed in a front panel.

FIGS. 9A-9D illustrate another embodiment of an optical communicationssystem that is configured to receive a Z-pluggable OCM and that includesan actuator mechanism for imparting motion in the downward and upwardY-directions to the Z pluggable OCM.

FIG. 10 illustrates one of the bays shown in FIGS. 9A-9D in itsdisassembled form to show the individual components of the bay.

FIGS. 11A and 11B illustrate front and back perspective views,respectively, of the bay shown in FIG. 10 in its assembled form.

FIGS. 12A and 12B illustrate front and back perspective views,respectively, of the heat sink structure shown in FIG. 10.

FIGS. 13 and 14 illustrate perspective views of the cam and the spindle,respectively, shown in FIG. 10.

FIGS. 15A-15D illustrate front perspective views of one of the baysshown in FIGS. 9A-9D as the parallel OCM disposed in the bay is movedfrom its raised position to its lowered position by the actuatormechanism shown in FIGS. 10-14.

FIG. 16 illustrates a perspective view of the strain relief devices andthe cables that are connected to the Z-pluggable OCMs shown in FIGS.6A-6E.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

In accordance with the invention, an EMI shielding device and method areprovided for use with an optical communications module (OCM) that isconfigured to be plugged into a front panel of a box or housing of anoptical communications system. The EMI shielding device is mechanicallycoupled to an end of a housing of the OCM such that when the OCM isfully inserted through an opening formed in the front panel, the EMIshielding device comes into abutment with the front panel to form an EMIseal around the opening that prevents, or at least helps prevent, EMIfrom escaping from the system housing through the opening formed in thefront panel.

In accordance with the illustrative embodiment, the EMI shielding deviceis used with a Z-pluggable optical communications module (OCM) thatcontains multiple parallel OCMs (POCMs) and that is configured to beremovably plugged into an opening formed in a front panel of an opticalcommunications system. When the Z-pluggable OCM is plugged in a forwardZ-direction into the opening formed in the front panel, an actuatormechanism imparts motion to the Z-pluggable OCM in the downwardY-direction to cause the Z-pluggable OCM to be mounted on an uppersurface of a motherboard PCB. In order to unplug the Z-pluggable OCM,the actuator mechanism imparts motion to the Z-pluggable OCM in theupward Y-direction to cause it to be dismounted from the motherboardPCB. Once dismounted from the motherboard PCB, a user may remove theZ-pluggable OCM from the system by exerting a force on the Z-pluggableOCM in the reverse Z-direction, i.e., in a direction normal to, and awayfrom, the front panel.

The Z-pluggable OCM is relatively long in the Z-dimension to accommodatethe plurality of parallel OCMs that are contained therein, which arecascaded in the Z-direction inside of the Z-pluggable OCM. However, theZ-pluggable OCMs are relatively narrow in the X-dimension. By making theZ-pluggable OCMs relatively long in the Z-dimension, a relatively largenumber of POCMs can be cascaded in the Z-direction inside of the module,which allows the X-dimension of the system to be kept relatively small.By keeping the module relatively narrow in the X-dimension, a largernumber of the Z-pluggable OCMs can be installed in the front panel toincrease edge-mounting density. The increase in the number of POCMs thatcan be cascaded in the Z-direction within each Z-pluggable OCM combinedwith the increased edge-mounting density allows a very high overallbandwidth to be achieved. In addition, the Z-pluggability of the moduleallows it to be easily installed and removed to provide many otheradvantages, such as, for example, the ability to easily replace one ofthe modules in the event of a part failure.

FIG. 3 illustrates a front perspective view of an optical communicationssystem 10 in accordance with an illustrative embodiment. A box, orhousing, 11 of the optical communications system 10 has a front panel 12with openings 13 formed in it for receiving respective Z-pluggable OCMs20. As will be described in more detail below, each of the Z-pluggableOCMs 20 has a metal housing 21 and a plurality of POCMs (not shown),which are mounted within the housing 21. Each of the Z-pluggable OCMs 20has an EMI shielding device 22 attached to one end of the metal housing21. The same end of the metal housing 21 is also attached to an end ofan optical fiber ribbon cable 23. As will be described below in moredetail, the EMI shielding device 22 performs EMI shielding functions.

FIG. 4 illustrates a perspective view of one of the Z-pluggable OCMs 20shown in FIG. 3 with one side of the housing 21 removed to reveal POCMs30 and a PCB 40 on which the POCMs 30 are mounted. In accordance withthis illustrative embodiment, four POCMs 30, each having six transmitchannels and six receive channels, are mounted on the PCB 40 andelectrically interconnected with the PCB 40. Thus, in accordance withthis embodiment, each ribbon cable 23 has twenty-four transmit fibersand twenty-four receive fibers. The invention, however, is not limitedwith respect to the number of POCMs 30 that are contained in eachZ-pluggable OCM 20, or with respect to the number of transmit and/orreceive channels that are provided in each POCM 30. The invention alsois not limited with respect to the number of optical fibers that arecontained in the ribbon cables 23.

With reference again to FIG. 3, although the Z-pluggable OCM 20 is notlimited to having any particular X, Y or Z dimensions, in accordancewith an illustrative embodiment, each Z-pluggable OCM 20 has a width inthe X-dimension of approximately 0.5 inches, which is about half thewidth of the parallel optical communications module 6 shown in FIGS. 1and 2. Even with this greatly reduced width, each Z-pluggable OCM 30provides about twice as many channels as the parallel opticalcommunications module 6. Thus, the edge-mounting configuration shown inFIG. 3 has a front panel mounting density that is about four timesgreater than that of the configuration shown in FIG. 2.

With reference again to FIG. 4, because of the high mounting density ofthe Z-pluggable OCMs 20 in the front panel 12, and because of the largenumber of channels that each Z-pluggable OCM 20 has, a relatively largeamount of heat will need to be dissipated in the system 10. For thisreason, the Z-pluggable OCM 20 of the embodiment shown in FIG. 4 hasbeen designed with separate heat sink structures for the ICs (not shown)and for the laser diodes (not shown). This feature allows the ICs andthe laser diodes to operate at different temperatures. One of the heatsink structures 50 is thermally coupled by the metal housing 21 to athermal pad (not shown) on which the ICs are mounted, while the other ofthe heat sink structures 60 is thermally coupled to a metal lead frame(not shown) on which the laser diodes are mounted. The heat sinkstructures 50 and 60 spread and dissipate heat generated by the ICs andby the laser diodes, respectively.

In addition to the heat spreading and dissipation functions that areperformed by the separate heat sink structures 50 and 60, the system 10preferably will include a cooling system (not shown) that will blow airthrough the metal housings 21 of the Z-pluggable OCMs 20 to facilitatecooling. Air that is blown through the heat sink structure 50 in theZ-direction will cool the ICs of the POCMs 30 whereas air that is blownthrough the heat sink structure 60 will cool the laser diodes of thePOCMs 30.

With reference to FIG. 4, the PCB 40 of the Z-pluggable OCM 20 hasarrays of electrically-conductive contacts (not shown) disposed on itslower surface that are electrically connected to the respective parallelOCMs 30. These arrays of electrically-conductive contacts come intocontact with respective arrays of electrically-conductive contactsdisposed on the upper surface of the motherboard PCB (not shown) of thesystem 10 (FIG. 3) when the Z-pluggable OCM 20 is edge-mounted in thefront panel 12 (FIG. 3), as will be described below in more detail withreference to FIGS. 5-6D.

The invention is not limited with respect to the type or configurationof the POCMs that are used in the Z-pluggable OCMs 20, or with respectto the manner in which the POCMs are mounted within the housing 21.Other examples of POCMs that are suitable for this purpose are disclosedin U.S. Pat. Nos. 7,331,720, and 8,036,500, which are assigned to theassignee of the present application and which are incorporated byreference herein in their entireties. A variety of other known POCMs arealso suitable for use with the invention, as will be understood bypersons skilled in the art in view of the description being providedherein.

FIG. 5 illustrates a front perspective view of the opticalcommunications system 10 shown in FIG. 3 with a portion of the metalsystem box, or housing, 11 and metal front panel 12 removed to reveal anactuator mechanism 70 disposed inside of the system box 11. The purposeof the actuator mechanism 70 is to impart motion to the Z-pluggable OCM20 in the downward and upward Y-directions to engage and disengage,respectively, the OCM 20 from arrays 71 of electrically-conductivecontacts disposed on an upper surface 72 a of a motherboard PCB 72. Inaccordance with this embodiment, the actuator mechanism 70 is ascrew-turn actuator that actuates a cam mechanism that lowers theZ-pluggable OCM 20 onto the upper surface 72 a of the motherboard PCB 72when an Acme screw 73 is turned in one direction and that lifts theZ-pluggable OCM 20 off of the upper surface 72 a of the motherboard PCB72 when the Acme screw 73 is turned in the opposite direction.

The actuator mechanism 70 includes a guide system 80 that is anelongated, generally rectangular structure having a cam follower 81integrally formed therein along upper edges of opposite sides of theguide system 80. Only one side 80 a of the guide system 80 is visible inFIG. 5, but the opposite side is structurally identical to side 80 a.The guide system 80 has a hanger 82 integrally formed therein along thelength of its lower surface 80 b. The housing 21 of the Z-pluggable OCM20 has a track 24 formed along the length of its upper surface 21 a. Thetrack 24 and the hanger 82 are sized and shaped to engage one anotherwhen the Z-pluggable OCM 20 is inserted through the front panel 12 inthe Z-direction with the track 24 and the hanger 82 aligned with oneanother. The guide system 80 guides the Z-pluggable OCM 20 in forwardZ-directions and reverse Z-directions into and out of the box 11,respectively. Once the Z-pluggable OCM 20 has been fully inserted intothe box 11, it is ready to be lowered down in the Y-direction onto theupper surface 72 a of the motherboard PCB 72 by the actuator mechanism70.

The Acme screw 73 of the actuator mechanism 70 includes a head 73 a anda threaded shaft (not shown), with the head 73 a being fixed to one endof the threaded shaft and in abutment with a metal bezel 12 a that issecured to the front panel 12. An Acme threaded nut 73 b is threadinglyengaged with the opposite end of the shaft and is rotationally coupledto a back vertical wall 75 a of a bay housing 75. A cam 90 is fixedlysecured to the shaft of the Acme screw 73 along its length. For thisreason, the shaft is not visible in FIG. 5. The cam 90 has a cam surface90 a formed in it that limits the direction of travel of the camfollower 81. When the Acme screw 73 is turned in the clockwisedirection, the cam 90 moves in the forward Z-direction indicated byarrow 63. When the cam 90 moves in this direction, the direction oftravel of the cam follower 81 causes the guide system 70 to be lowered,i.e., to move in the downward Y-direction. When the Acme screw 73 isturned in the counter clockwise direction, the cam 90 moves in thereverse Z-direction indicated by arrow 64. When the cam 90 moves in thisdirection, the direction of travel of the cam follower 81 causes theguide system 70 to be lifted, i.e., to move in the upward Y-direction.

After the Z-pluggable OCM 20 has been fully inserted through the frontpanel 12 such that the EMI shielding device 22 is in abutment with thebezel 12 a, the person installing the OCM 20 turns the head 73 a of theAcme screw 73 by two turns in the counter clockwise direction to causethe OCM 20 to be lowered (i.e., moved in the downward Y-direction) ontothe upper surface 72 a of the motherboard PCB 72. When the OCM 20 hasbeen fully lowered onto the upper surface 72 a of the motherboard PCB72, the arrays of electrically-conductive contacts that are disposed onthe lower surface of the PCB 40 (FIG. 4) of the OCM 20 come into contactwith the respective arrays 71 of electrically-conductive contactsdisposed on the upper surface 72 a of the motherboard PCB 72. To removethe OCM 20 from the system 10, the person removing the OCM 20 turns thehead 73 a of the Acme screw 73 by two turns in the clockwise directionto cause the OCM 20 to be lifted (i.e., moved in the upward Y-direction)off of the motherboard PCB 72. The person can then remove the OCM 20from the system 10 by sliding the OCM 20 in the reverse Z-direction awayfrom, and generally perpendicular to, the front panel 12. Of course, twoturns is not the only thread pitch that may be used for this purpose, sothis is merely an example of the manner in which the screw-turn actuatormechanism 70 may operate.

FIGS. 6A-6E illustrate perspective views of an optical communicationssystem 100 that employs a spring-loaded actuator mechanism 110 to impartmotion in the upward and downward Y-directions to a Z-pluggable OCM 120.The optical communications system 100 includes a metal system box, orhousing, 101 having a front panel 102. The sides of the box 101 havebeen removed in FIGS. 6A-6E to make it easier to see the spring-loadedactuator mechanism 110. A motherboard PCB 103 is mounted on an uppersurface of a bottom panel 104 of the box 101. A plurality of Meg-arraysockets 105 that are similar or identical to the socket 4 shown in FIGS.1 and 2 are mounted on the upper surface 103 a of the motherboard PCB103. The number of Meg-array sockets 105 that are mounted on themotherboard PCB 103 in the Z-direction is equal to the number of POCMs106 that are included in each of the Z-pluggable OCMs 120.

FIG. 6A illustrates the optical communications system 100 and one of theZ-pluggable OCMs 120 prior to the OCM 120 being inserted in the forwardZ-direction through an opening formed in the front panel 102. FIG. 6Billustrates the optical communications system 100 and one of theZ-pluggable OCMs 120 after the OCM 120 has been fully inserted into thesystem 100, but just prior to the spring-loaded actuator mechanism 110being triggered. FIG. 6C illustrates the optical communications system100 and one of the Z-pluggable OCMs 120 just after the spring-loadedactuator mechanism 110 has been triggered, but prior to all of theenergy that is stored in a main compression spring 111 of the actuatormechanism 110 being released. FIG. 6D illustrates the opticalcommunications system 100 and one of the Z-pluggable OCMs 120 after thespring-loaded actuator mechanism 110 has been triggered and all of theenergy that was stored in the main spring 111 has been released to causea cam (not shown) to force the Z-pluggable OCM 120 in the downwardY-direction onto the upper surface 103 a of the motherboard PCB 103.FIG. 6E illustrates the optical communications system 100 with one ofthe Z-pluggable OCMs 120 fully inserted into the system 100 after arelease pushbutton 130 has been depressed by a user to cause a cam (notshown) of the spring-loaded actuator mechanism 110 to lift theZ-pluggable OCM 120 in the upward Y-direction off of the upper surface103 a of the motherboard PCB 103. The manner in which the spring-loadedactuator mechanism 110 operates will now be described with reference toFIGS. 6A-6E.

The spring-loaded actuator mechanism 110 includes the main spring 111, abase 112, a screw 113, a slider 114, a release trigger 116, a verticalsupport 117, a down trigger 118, and cams (not shown) that are housedwithin the guide system 140. A proximal end of the spring 111 is fixedlysecured to the base 112. A proximal end of the screw 113 is also fixedlysecured to the base 112. A shaft 113 a of the screw 113 is slidable inthe Z-directions through an opening formed in the slider 114. Therelease trigger 116 is rotationally coupled on its proximal end to thebase 112. The release trigger 116 is in pivotal contact on its distalend to pins 121 disposed on opposite sides of vertical support 117 whenthe actuator mechanism 110 is in the rearward state, or position, shownin FIG. 6B. The down trigger 118 has a proximal end that is disposed infree space to come into contact with a head 113 b of the screw 113 whenthe spring-loaded actuator 110 is in its rearward position shown in FIG.6B. A distal end of the down trigger 118 is mechanically coupled to therelease trigger 116.

When the Z-pluggable OCM 120 is inserted through the front panel 102 inthe Z-direction into the interior of the box 101, the upper surface 131a of the housing 131 of the Z-pluggable OCM 120 engages thespring-loaded actuator mechanism 110, which is movable in the forwardand reverse Z-directions within the guide system 140. The force exertedon the Z-pluggable OCM 120 in the forward Z-direction pushes thespring-loaded actuator 110 in the forward Z-direction until thespring-loaded actuator 110 is in its rearward position, as shown in FIG.6B. As the spring-loaded actuator 110 travels in this direction, thedistance between the base 112 and the slider 114 decreases, therebycausing the main spring 111 to become compressed. As the spring-loadedactuator mechanism 110 travels in this direction, the shaft 113 a of thescrew 113 slides through the opening formed in the slider 114 to extendin the direction indicated by arrow 145. When the spring-loaded actuatormechanism 110 arrives at its rearward position, the head 113 b of thescrew 113 comes into contact with the proximal end of the down trigger118.

The down trigger 118 is essentially a lever such that the force appliedby the head 113 b of the screw 113 on the proximal end of the downtrigger 116 causes the distal end of the down trigger 118 to move in theupward Y-direction. When the distal end of the down trigger 118 moves inthis direction, the down trigger 118 triggers the release trigger 116 bydisengaging the distal end of the release trigger 116 from the pins 121.When this happens, the energy stored in the main spring 111 is released,which forces the spring-loaded actuator mechanism 110 to move from itsrearward position shown in FIG. 6B toward its forward position shown inFIG. 6D. As the spring-loaded actuator mechanism 110 moves from itsrearward position shown in FIG. 6B to its forward position shown in FIG.7D, the spring-loaded actuator mechanism 110 actuates a cam (not shown)of the guide mechanism 140 that pushes the Z-pluggable OCM 120 in thedownward Y-direction to cause the electrically-conductive contacts (notshown) disposed on the lower surface of the PCB (not shown) of the OCM120 to come into contact with the electrically-conductive contacts (notshown) disposed within the respective Meg-array sockets 105.

With reference to FIG. 6E, the optical communications system 100 alsoincludes a spring-loaded pushbutton mechanism comprising the releasepushbutton 130 and a compression spring 135. A first portion 130 a ofthe release pushbutton 130 extends through an opening 130 c formed inthe front panel 102. A second portion 130 b of the pushbutton 130extends behind the front panel 102. The compression spring 135 has aproximal end that is mechanically coupled with the second portion 130 bof the pushbutton 130 and a distal end that abuts the spring-loadedactuator mechanism 110. When the Z-pluggable OCM 120 is in thein-and-down position shown in FIG. 6D, the pushbutton 130 is fullyextended from the front panel 102. If the pushbutton 130 is pressed inthe inward Z-direction until the first portion 130 a of the pushbutton130 is almost flush with the front panel 102, the distal end of thecompression spring 135 will exert a force on the spring-loaded actuatormechanism 110 that will force it in the rearward Z-direction. When thishappens, a cam (not shown) housed within the guide system 140 exerts aforce on the Z-pluggable OCM 120 in the upward Y-direction that willcause the Z-pluggable OCM 120 to disengage from the motherboard PCB 103.The user can then extract the Z-pluggable OCM 120 from the system 100 byexerting a force on it in reverse Z-direction, i.e., away from the frontpanel 102.

The Z-pluggable OCM 120 includes an EMI shielding device 160 (FIGS.6A-6E) that is similar or identical to the EMI shielding device 22(FIGS. 3-5). The EMI shielding devices 22 are made of a metallicmaterial such as, for example, sheet metal or metal foil, both of whichare solid materials and yet provide a degree of flexibility. As can bemore clearly seen in FIG. 4, the portion 22 a of the EMI shieldingdevice 22 curves inwardly on all sides. When the Z-pluggable OCM 20 isin its fully-inserted position, the portion 22 a is in abutment with thebezel 12 a installed on the front panel 12. The flexibility of the EMIshielding device 22 allows portion 22 a to deform slightly to ensurethat it is in continuous contact with the metal bezel 12 a. Once theZ-pluggable OCM 20 has been placed in its fully inserted position, theportion 22 a remains in continuous contact with the bezel 12 a even asthe Z-pluggable OCM 20 is moved in the upward and downward Y-directionsby the actuator mechanism 70.

The same is true for the EMI shielding device 160 shown in FIGS. 6A-6E.For example, it can be seen in FIGS. 6B-6D that the EMI shielding device160 remains in abutment with the front panel 102 during the lowering andraising of the Z-pluggable OCM 120 in the downward and upwardY-directions. Both of the EMI shielding devices 22 and 160 providerobust EMI shielding solutions. It can also be seen in FIGS. 3 and 5that the bezel 12 a has walls 12 a′ on opposite sides of the bezel 12 athat protrude from the bezel 12 a in the rearward Z-direction. Thesewalls 12 a′ are in abutment with the portions 22 a of the respective EMIshielding devices 22 of the Z-pluggable OCMs 20 that are inserted intothe system 10 adjacent to these walls 12 a′. This feature furtherprevents air gaps from existing at the front panel 12, which ensuresthat very little, if any, EMI escapes from the box 11 through the frontpanel 12.

FIGS. 7A and 7B illustrate top perspective views of two of the adjacentZ-pluggable OCMs 20 shown in FIGS. 3-5 without the box 11. FIG. 8illustrates a top perspective view of a plurality of adjacentZ-pluggable OCMs 20 shown in FIGS. 3-5 plugged into adjacent openings 13formed in the front panel 12, but the front panel 12 is not shown toallow the abutting portions 22 a of adjacent EMI shielding devices 22 tobe clearly seen. It can be seen in these figures that the portion 22 aof each EMI shielding device 20 remains in continuous contact with theportion 22 a of the adjacent EMI shielding device 20 as relativemovement occurs between the OCMs 20 in the upward or downwardY-directions.

Thus, there is continuous contact between adjacent portions 22 a ofadjacent EMI shielding devices 22, between each portion 22 a of each EMIshielding device 22 and the bezel 12 a (FIGS. 3 and 5), and between theportions 22 a of the EMI shielding devices 22 positioned on oppositeends of the front panel 12 and the walls 12 a′ of the bezel 12 a. Thiscontinuous contact ensures that EMI shielding at the front panel 12occurs at all times during sliding in the upward or downward directionsof the OCMs 20. The portions 22 a are non-segmented so that they do notsnag on the portions 22 a of adjacent EMI shielding devices 22 as therespective OCMs 20 move in the upward or downward Y-directions. Each EMIshielding device 22 comprises a plurality of the portions 22 a, and theportions 22 a of each EMI shielding device 22 are interconnected to forman EMI seal that surrounds the respective opening 13. The EMI seal isdepicted as being rectangular in shape, but the seal may have any shapethat suitably surrounds the opening 13 (e.g., square, circular, oval,etc.). Also, although each EMI shielding device 22 is shown as beingmade up of multiple interconnected portions 22 a, the EMI shieldingdevice 22 could be made up of a single, or unitary, element that issuitably shaped to surround the opening 13 to form the EMI seal.

In accordance with the illustrative embodiment, the portions 22 a arerounded elements, or rounds. Using rounds for the portions 22 a ensuresthat there is continuous line contact at locations where the portions 22a come into contact with a portion 22 a of an adjacent EMI shieldingdevice 22, with the bezel 12 a (FIGS. 3 and 5), or with one of the walls12 a′ of the bezel 12 a. This continuous line contact ensures that thereis a good EMI seal between the portions 22 a of adjacent EMI shieldingdevices 22, between each portion 22 a of each EMI shielding device 22and the bezel 12 a (FIGS. 3 and 5), and between the portions 22 a of theEMI shielding device 22 positioned on opposite ends of the front panel12 and the walls 12 a′ of the bezel 12 a.

In addition, making the portions 22 a rounds gives the portions 22 a aflexibility, or spring characteristics. These spring characteristicsallow the portions 22 a of adjacent EMI shielding devices 22 to deformwhen a sufficient force is exerted against them, which causes theportions 22 a to conform to surfaces with which they come into contact(i.e., the portion 22 a of an adjacent EMI shielding device 22, thebezel 12 a or the walls 12 a′). The continuous line contact incombination with the conforming characteristics of portions 22 a ensuresthat there is a very good EMI seal about the openings 13, and thus veryrobust EMI shielding at the front panel 12.

FIGS. 9A-9D illustrate another embodiment of an optical communicationssystem 200 that is configured to receive a Z-pluggable OCM 210 and thatincludes an actuator mechanism (not shown) for imparting motion in thedownward and upward Y-directions to the Z-pluggable OCM 210 to cause itto engage and disengage, respectively, a motherboard PCB 220 of thesystem 200. FIG. 9A illustrates a front perspective view of the opticalcommunications system 200 just prior to the Z-pluggable OCM 210 beinginserted through an opening 212 a formed in a front panel 212 of thesystem 200. FIG. 9B illustrates a front perspective view of the opticalcommunications system 200 after the Z-pluggable OCM 210 has been fullyinserted into the system 200, but prior to the Z-pluggable OCM 210 beinglowered by the actuator mechanism (not shown) to engage the motherboardPCB 220. FIG. 9C illustrates a front perspective view of the opticalcommunications system 200 after the Z-pluggable OCM 210 has been fullyinserted into the system 200 and after the Z-pluggable OCM 210 has beenlowered by the actuator mechanism (not shown) to engage the motherboardPCB 220. FIG. 9D illustrates a front perspective view of the opticalcommunications system 200 with the Z-pluggable OCM 210 in the fullyinserted and engaged position shown in FIG. 9C with an optical connectormodule 230 connected to the Z-pluggable OCM 210.

The embodiment of the optical communications system 200 shown in FIGS.9A-9D has multiple bays 240 that are identically configured to receiverespective Z-pluggable OCMs 210. The configurations of the bays 240 willbe described with reference to FIGS. 10-14. FIG. 10 illustrates one ofthe bays 240 in its disassembled form to show the individual componentsof the bay 240. The bay 240 is made up of a frame 241, a heat sinkstructure 242, a cam 243, a spindle 244, and a retaining clip 245. FIGS.11A and 11B illustrate front and back perspective views, respectively,of the bay 240 shown in FIG. 10 in its assembled form. FIGS. 12A and 12Billustrate front and back perspective views, respectively, of the heatsink structure 242 shown in FIG. 10. FIGS. 13 and 14 illustrateperspective views of the cam 243 and the spindle 244, respectively.

The manner in which the bay 240 is assembled will now be described withreference to FIG. 10-14. As shown in FIGS. 12A and 12B, first and secondcams 243 a and 243 b are inserted into cam follower pockets 242 a and242 b formed in opposite ends of the heat sink structure 242. A verticalslot 242 c to allow movement of the spindle 244 extends from a front end242 d of the heat sink structure 242 to a back end 242 e of the heatsink structure 242. As best seen in FIGS. 10-11B, after the cams 243 aand 243 b have been positioned within the cam follower pockets 242 a and242 b, the heat sink structure 242 is inserted within the frame 241 suchthat the front end 242 d of the heat sink structure 242 is adjacent aninner surface of a front wall 241 a of the frame 241 and such that theback end 242 e of the heat sink structure 242 is adjacent an innersurface of a back wall 241 b of the frame 241.

After the heat sink structure 242 having the cams 243 a and 243 bpositioned therein has been secured to the frame 241, a distal end ofthe spindle 244 is inserted through first and second thru holes 241 cand 241 d formed in the front and back walls 241 a and 241 b,respectively, of the frame 241 and through the offset holes 243 c formedin the cams 243 a and 243 b (FIG. 13). The offset holes 243 c each havea cylindrically-shaped inner surface portion 243 d and a flat innersurface portion 243 e that together form keyways in the cams 243 a and243 b. The spindle 244 has a slotted, hexagonal head 244 a and a shaft244 b. The shaft 244 b has a cylindrically-shaped outer surface portion244 c and a flat outer surface portion 244 d that together form a key.When the spindle 244 is inserted into the offset holes 243 c formed inthe cams 243 a and 243 b, the cylindrically-shaped inner surfaceportions 243 d of the offset holes 243 c are in contact with thecylindrically-shaped outer surface portion 244 c of the shaft 244 b, andthe flat inner surface portions 243 e of the offset holes 243 c are incontact with the flat outer surface portion 244 d of the shaft 244 b. Inthis way, the spindle 244 couples with the cams 243 a and 243 b in akey/keyway coupling configuration.

When the bay 240 is in its assembled form shown in FIGS. 11A and 11B,the slotted, hexagonal head 244 a of the spindle 244 is in abutment withan outer surface of the front wall 241 a of the frame 241. The retainingclip 245 is then clipped into a retaining clip groove 244 e shown inFIG. 14 such that the retaining clip 245 is in abutment with the outersurface of the back wall 241 b of the frame 241, as shown in FIG. 11B.The frame 241 is secured to the upper surface of the motherboard PCB 220via fastening devices (not shown) that are inserted through openings 246a formed in feet 246 of the frame 241.

The actuator mechanism, in accordance with this illustrative embodiment,is made up of portions of the frame 241, the heat sink structure 242,the cams 243 a and 243 b, the spindle 244, and the retaining clip 245.As shown in FIG. 12B, the heat sink structure 242 has rails 251 formedon opposite sides thereof that engage rails 211 (FIG. 9A) formed onopposite sides of the Z-pluggable OCM 210 when it is inserted into theopening 212 a formed in the front panel 212 (FIG. 9B).

Once the Z-pluggable OCM 210 has been fully inserted into the bay 240,as shown in FIG. 9B, it is ready to be lowered onto the motherboard PCB220. One or more Meg-array sockets 221 (FIGS. 9A and 9B) of the typeshown in FIGS. 1 and 2 are mounted on the upper surface 220 a of themotherboard PCB 220 within the bays 240. The lower surface of the PCB(not shown) of the Z-pluggable OCM 210 has one or more Meg-arrayconnectors (not shown) thereon for mating with respective Meg-arraysockets 221. To lower the Z-pluggable OCM 210 onto the motherboard PCB220 and to raise the Z-pluggable OCM 210 onto the motherboard PCB 220,the user uses a screwdriver or the like to turn the head 244 a of thespindle 244, as will now be described with reference to FIGS. 15A-15D.

In FIG. 15A, the Z-pluggable OCB 210 is in its raised position. As theuser turns the head 244 a of the spindle 244 in the counterclockwisedirection, the cams 243 a and 243 b move within the cam follower pocket242 a and 242 b of the heat sink structure 242 from the position shownin FIG. 15A where they are applying an upwardly-directed force againstthe top of the pockets 242 a and 242 b to the position shown in FIGS.15B-15D where they are applying a downwardly-directed force against thebottoms of the pockets 242 a and 242 b. In FIG. 15D, the Meg-arrayconnectors (not shown) on the lower surface of the PCB of the OCM 210are connected with the Meg-array sockets 221 disposed on the motherboardPCB 220. Turning the head 244 a of the spindle 244 in the oppositedirection will cause the OCM 210 to be raised in the Y-direction awayfrom the motherboard PCB 220 to allow the OCM 210 to be removed from thesystem 200.

FIG. 16 illustrates a perspective view of the strain relief devices andthe cables 161 that are connected to the Z-pluggable OCMs 120 shown inFIGS. 6A-6E. Because the Z-pluggable OCMs 120 can be so densely mountedon the front panel 102, traditional strain relief components, such asrubber boots, may not provide sufficient bend resistance for the cables161. In accordance with an illustrative embodiment, the strain reliefdevices include groups 162 of metal wires, or rods, 163 that are clampedbetween first and second clamps 164 and 165. The metal wires 163 may be,for example, 0.015 inches in diameter. The wire groups 162 aresufficiently strong to prevent the cables 161 from being bent beyondtheir minimum allowable bend radii. The strength of the wire groups 162can also be easily tuned by using more or fewer wires 163 in each group162.

The invention has been described with reference to a few illustrative,or exemplary, embodiments for the purpose of describing the principlesand concepts of the invention. Those skilled in the art will understandthat the invention is not limited to these illustrative embodiments. Forexample, although the EMI shielding device and method have beendescribed as being used with a Z-pluggable OCM, the invention is notlimited with respect to the type of OCM that uses the EMI shieldingdevice and method. As will be understood by those skilled in the art inview of the description being provided herein, modifications may be madeto the embodiments described herein while still achieving the goals ofthe invention, and all such modifications are within the scope of theinvention.

What is claimed is:
 1. A Z-pluggable optical communications module (OCM)comprising: a generally rectangular module housing, the module housingbeing configured to be inserted through an opening formed in a frontpanel of a box in a Z-direction of an X, Y, Z Cartesian Coordinatesystem, wherein the box houses an optical communications system; a firstcircuit board disposed within the housing; at least one parallel opticalcommunications module (POCM) mounted on the first circuit board, said atleast one POCM having a plurality of channels, each of the channelsbeing either a transmit channel for transmitting optical data signals ora receive channel for receiving optical data signals; first ends ofoptical fibers of an optical fiber cable being connected to said atleast one POCM, wherein the first ends are received in the modulehousing through an opening formed in a first end of the module housing;and an electromagnetic interference (EMI) shielding device fixedlysecured to or integrally formed in the first end of the module housingsuch that when the module housing is fully inserted through the openingformed in the front panel of the box in the Z-direction of the X, Y, ZCartesian Coordinate system, the EMI shielding device abuts the frontpanel and surrounds the opening to form an EMI seal about the openingthat prevents, or at least helps prevent, EMI from escaping from themodule housing through the opening.
 2. The Z-pluggable OCM of claim 1,wherein the EMI shielding device comprises a plurality of interconnectedportions, and wherein each portion of the EMI shielding device is anon-segmented portion.
 3. The Z-pluggable OCM of claim 2, wherein eachnon-segmented portion is a round such that the abutment of each of theportions with the front panel constitutes a continuous line contactbetween the respective portion and the front panel.
 4. The Z-pluggableOCM of claim 3, wherein each of the non-segmented portions is made of athin piece of metal that is rounded to form the respective rounds, andwherein each round has spring characteristics that allow the round todeform when the round abuts a surface such that the deforming roundconforms to the abutting surface.
 5. The Z-pluggable OCM of claim 1,wherein the EMI shielding device remains in sliding abutment with thefront panel even as the Z-pluggable OCM is moved in upward or downwardY-directions of the X, Y, Z Cartesian Coordinate system.
 6. An opticalcommunications system comprising: a system housing having at least abottom panel and a front panel, the front panel residing in an X-Y planethat is orthogonal to a forward Z-direction and to a reverseZ-direction; a plurality of Z-pluggable OCMs disposed within respectiveopenings formed in the front panel of the system housing, eachZ-pluggable OCM including a respective module housing having arespective electromagnetic interference (EMI) shielding device fixedlysecured to or integrally formed in a first end of the respective modulehousing that comes into abutment with the front panel when the modulehousing is fully inserted into the respective opening formed in thefront panel, and wherein each respective EMI shielding device surroundsthe respective opening to form an EMI seal about the respective openingthat prevents, or helps prevent, EMI from escaping from the modulehousing through the opening.
 7. The optical communications system ofclaim 6, wherein each EMI shielding device is also in abutment with atleast one adjacent EMI shielding device.
 8. The optical communicationssystem of claim 7, wherein each EMI shielding device comprises aplurality of interconnected portions, and wherein each portion of therespective EMI shielding device is a non-segmented portion.
 9. Theoptical communications system of claim 8, wherein each non-segmentedportion is a round such that the abutment of each of the portions withthe front panel constitutes a continuous line contact between therespective portion and the front panel.
 10. The optical communicationssystem of claim 9, wherein each of the non-segmented portions is made ofa thin piece of metal that is rounded to form the respective rounds, andwherein each round has spring characteristics that allow the round todeform when the round abuts a surface such that the deforming roundconforms to the abutting surface.
 11. The optical communications systemof claim 6, wherein the EMI shielding devices remain in sliding abutmentwith the front panel even as the Z-pluggable OCMs are moved in upward ordownward Y-directions of the X, Y, Z Cartesian Coordinate system.
 12. Amethod for performing electromagnetic interference (EMI) shielding in anoptical communications system, the method comprising: providing aZ-pluggable optical communications module (OCM) comprising a generallyrectangular module housing configured to be inserted through an openingformed in a front panel of a box in a Z-direction of an X, Y, ZCartesian Coordinate system, wherein a first circuit board is disposedwithin the module housing and at least one parallel opticalcommunications module (POCM) is mounted on the first circuit board saidat least one POCM having a plurality of channels, each of the channelsbeing either a transmit channel for transmitting optical data signals ora receive channel for receiving optical data signals, and wherein firstends of optical fibers of an optical fiber cable are connected to saidat least one POCM and are received into the module housing through anopening formed in a first end of the module housing, and wherein anelectromagnetic interference (EMI) shielding device is fixedly securedto or integrally formed in the first end of the module housing; andfully inserting the module housing through the opening formed in thefront panel of the box in the Z-direction of the X, Y, Z CartesianCoordinate system until the EMI shielding device abuts the front panel,and wherein the EMI shielding device surrounds the opening to form anEMI seal about the opening that prevents, or at least helps prevent, EMIfrom escaping from the module housing through the opening.
 13. Themethod of claim 12, wherein the EMI shielding device comprises aplurality of interconnected portions, and wherein each portion of theEMI shielding device is a non-segmented portion.
 14. The method of claim13, wherein each non-segmented portion is a round such that the abutmentof each of the portions with the front panel constitutes a continuousline contact between the respective portion and the front panel.
 15. Themethod of claim 14, wherein each of the non-segmented portions is madeof a thin piece of metal that is rounded to form the respective rounds,and wherein each round has spring characteristics that allow the roundto deform when the round abuts a surface such that the deforming roundconforms to the abutting surface.
 16. The method of claim 12, whereinthe EMI shielding device remains in sliding abutment with the frontpanel even as the Z-pluggable OCM is moved in upward or downwardY-directions of the X, Y, Z Cartesian Coordinate system.
 17. A methodfor performing electromagnetic interference (EMI) shielding in anoptical communications system, the method comprising: providing aplurality of Z-pluggable optical communications modules (OCMs), eachZ-pluggable OCM comprising a generally rectangular module housingconfigured to be inserted through an opening formed in a front panel ofa box in a Z-direction of an X, Y, Z Cartesian Coordinate system,wherein each module housing has a first circuit board disposed withinthe module housing and at least one parallel optical communicationsmodule (POCM) mounted on the respective first circuit board, each POCMhaving a plurality of channels, each of the channels being either atransmit channel for transmitting optical data signals or a receivechannel for receiving optical data signals, and each module housing hasan electromagnetic interference (EMI) shielding device fixedly securedto or integrally formed in first end of the respective module housing;and fully inserting the module housings through respective openingsformed in the front panel of the box in the Z-direction of the X, Y, ZCartesian Coordinate system until the EMI shielding devices abut thefront panel, and wherein the EMI shielding devices surround therespective openings to form respective EMI seals about the respectiveopenings that prevent, or at least help prevent, EMI from escaping fromthe module housings through the openings.
 18. The method of claim 17,wherein each of the EMI shielding devices comprises a plurality ofinterconnected portions, and wherein each portion of the respective EMIshielding device is a non-segmented portion.
 19. The method of claim 18,wherein each non-segmented portion is a round such that the abutment ofeach of the portions with the front panel constitutes a continuous linecontact between the respective portion and the front panel.
 20. Themethod of claim 19, wherein each of the non-segmented portions is madeof a thin piece of metal that is rounded to form the respective rounds,and wherein each round has spring characteristics that allow the roundto deform when the round abuts a surface such that the deforming roundconforms to the abutting surface.
 21. The method of claim 17, whereinthe EMI shielding devices remain in sliding abutment with the frontpanel even as the Z-pluggable OCMs are moved in upward or downwardY-directions of the X, Y, Z Cartesian Coordinate system.